Automatic valving device

ABSTRACT

An automatic valving device, comprises a receiver for liquid, an elongated float structure disposed generally vertically in the receiver and including an upper float portion positioned in an upper region of the receiver and a lower float portion positioned in a lower region of the receiver, inlet and outlet port means for the receiver, and discharge valve means for the receiver coupled to the outlet port means. The float structure is coupled to the outlet port means and to the discharge valve means for opening and closing the discharge valve means for opening and closing the discharge valve means in response to changes in liquid level in the receiver. Biasing means are coupled to the discharge valve means for urging the discharge valve means to its closed position. The buoyancy of the float structure lower portion although submerged is insufficient to overcome the biasing means and to open the discharge valve means when closed, and the buoyancy of the float structure lower portion when fully submerged together with the buoyancy of the float structure upper portion when at least partially submerged is sufficient to overcome the biasing means and to open the discharge valve means at an upper limit level of liquid in the receiver. The total weight of the float structure and of the coupling thereof to the discharge valve means in conjunction with the biasing means is capable of closing the discharge valve means at a lower limit level of liquid in the receiver against the buoyancy of the float structure lower portion when at least partially submerged.

nited Sates Hankison et all.

aten [54] AUTOMATIC VALVING DEVICE [72] Inventors: Paul M. Hankison, Peters Township; Willlam Foster Walker, Bethel Park Borough, both of Pa.

[73} Assignee: Hankison Corporation, Cononsburg, Pa.

[22] Filed: Jan. 119, 1970 [21] Appl. No.: 3,880

FOREIGN PATENTS OR APPLICATIONS 346,212 1904 France ..137/l92 Primary Examiner-A1an Cohan Attorney-Don J. Smith [57] ABSTRACT An automatic valving device, comprises a receiver for liquid, an elongated float structure disposed generally vertically in the receiver and including an upper float portion positioned in an upper region of the receiver and a lower float portion positioned in a lower region of the receiver, inlet and outlet port means for the receiver, and discharge valve means for the receiver coupled to the outlet port means. The float structure is coupled to the outlet port means and to the discharge valve means for opening and closing the discharge valve means for opening and closing the discharge valve means in response to changes in liquid level in the receiver. Biasing means are coupled to the discharge valve means for urging the discharge valve means to its closed position. The buoyancy of the float structure lower portion although submerged is insufi'lcient to overcome the biasing means and to open the discharge valve means when closed, and the buoyancy of the float structure lower portion when fully submerged together with the buoyancy of the float structure upper portion when at least partially submerged is sufficient to overcome the biasing means and to open the discharge valve means at an upper limit level of liquid in the receiver. The total weight of the float structure and of the coupling thereof to the discharge valve means in ;conjunction with the biasing means is capable of closing the 21 Claims, 5 Drawing Figures PATENTED A IBTE 3.635.238

SHEEJ 1 BF 4 A E/V7 03! PM M HamZLfa/L ma! IZ dawn ibrer WaMel? PATENTEDJAMIQR 3 535238 sum u UF 4 AUTOMATIC VALVING DEVICE The present invention relates to an automatic valving device and more particularly to fast-acting means for automatically valving a liquid for the purpose of trap discharging, liquid level control, and the like, and in this connection the valving device is controlled by a float structure. Our invention includes novel means for increasing the capacity of the trap or other arrangement involving the valving device and for skimming a lighter or secondary liquid such as oil from the surface of a primary liquid contained within the arrangement.

This invention is an improvement upon certain aspects of our invention entitled Device for Automatically Valving Liquid" and described and claimed in our U.S. Pat. No. 2,999,509, issued Sept. 12, 1961.

The automatic valving device of our inventions is useful in a large number of applications wherein it is necessary or desirable to discharge periodically quantities of liquids from the system. Many of such applications involve movement of rather large amounts of air or other gas frequently under pressure, in which quantities of moisture, oil or other contaminating liquid tends to accumulate. These liquids must be discharged from the system without significant loss of pressure or of compressed fluid.

Numerous prior devices of difiering kinds have been proposed for the discharge of condensate or other liquid from traps and similar arrangements which are widely employed in industry, and for regulating the height of liquid in industrial vessels, receivers, in household tanks including toilet tanks, and elsewhere. The level of liquid in these arrangements frequently is controlled by intake or discharge of liquid therefrom as the case may be, when the liquid interface reaches a preselected level, by use of float operators, diaphragms, and spring members, both balanced and unbalanced. Recurring problems with such prior devices have included undesirable size or complexity of equipment, unwanted duration and velocity of liquid flow therethrough, clogging and other difficulties, or failures in service, and in some cases, the presence of unsafe operating conditions in the event of failure of the equipment. A further difficulty in some prior practices arose out of attempts to utilize pressure in the system to operate a device with the required certainty or precision and particularly where relatively smaller orifices and/or higher velocities were prescribed or required.

Examples of such devices are illustrated in the US. Pat. Nos. to Patterson 1,961,448; Nisley 1,176,091; Flaherty 2,158,750; Graham 2,258,450; Murray 729,956; Hammel 1,304,562; Ford 673,250; Kelley 2,760,596 and Faust et al. 2,726,732.

The aforementioned difiiculties have been largely overcome by the invention of our aforementioned patent. There are many applications, however, wherein the accumulation of moisture, oil or other contaminating liquid within the system is relatively great such that the automatic valving device either must be operated too frequently thereby causing undue wear, or the device is otherwise not endowed with sufficient capacity to handle the contaminating liquid to be discharged. It is desirable therefore to provide some means for increasing the volumetric capacity of the trap or other arrangement utilizing our novel automatic valving device.

In many applications, for example those involving compressed air, the compressor or similar device unavoidably injects a certain amount of lubricating oil into the system. The oil should be periodically discharged from the system, e.g., by collection in and drainage from a liquid trap, usually the same trap as that employed for removing moisture from the system. To prevent a buildup of oil or other lighter liquid on the surface of the water or other primary liquid it is desirable to skim any overlying oil layer each time the automatic valving means is actuated. If the oil is not periodically removed in the, same manner, the overlying oil layer increases in depth and distorts the operation of the automatic valving device, for example by modifying its valve open and valve close points, and in extreme cases deteriorates its functioning to the point of inoperability.

Among the aforementioned references, the US. Pat. Nos. to Kelley 2,760,596; Hammel 1,304,562 and Murray 729,956 disclose various types of traps having tubulated outlet passages. Such outlets do not function as skimming means, as these outlets have no provision for periodically drawing off substantially the entire liquid surface or interface. Although somewhat differing outlet structures are incorporated into the traps illustrated in the U.S. Pat. Nos. to Ford 673,250 and Nisley 1,176,091, the problem confronting the present invention still remains, as there is no adequate provision or opportunity for skimming of an overlying oil layer. Graham US. Pat. No. 2,258,450 is addressed to the separate elimination of gases and vapors on the one hand and a liquid refrigerant on the other. In the Graham structure, there is likewise no means for skimming an overlying layer of oil just before the discharge valve closes or at any time during the discharge cycle.

None of the cited references discloses means for increasing the volumetric capacity of a discharge trap or other equipment employing our novel automatic valving device, particularly within the context of a pressure-operated valving device such as that disclosed in our aforementioned patent.

We overcome the aforementioned disadvantages of the prior art by providing the oil skimming means which can be utilized with the automatic valving means of our aforementioned patent or with a number of differing trap constructions. Our novel oil skimmer, which is significantly noncomplex in construction is capable of a variety of applications outside of the fields of automatically drained traps and automatic valving devices. in the construction of the oil skimmer proper there are essentially no moving components such that the skimming means is not subject to wear or deterioration in use. The oil skimmer in effect does not become operative until the overlying oil or other lighter liquid approaches the skimmer. With its association with the outlet port structure of the device in which the skimmer is used, space requirements within the device are inconsequential and the liquid containment volume is not appreciably reduced thereby. The oil skimmer does not interfere with the primary operation of the automatic valving device, suchas that described herein or in our aforementioned patent.

We also disclose novel means for substantially increasing the volumetric capacity of an automatic drain trap or similar 1 automatically valved enclosure. Such means are described herein as an adjunct to the automatic valving device disclosed in our aforementioned patent. It will be apparent however as this description proceeds that the device can be employed with other automatic, valved arrangements. Thus, our automatic valving device is employed in a unique arrangement of a pair of floats and counterweighted catch means such that the automatic valve means can be opened and closed at widely separating levels of liquid in a reservoir therefor. An important aspect of our invention is a float arrangement whereby the pair of floats can be spatially separated to any convenient distance with no substantial modification of our novel valving device other than shortening or lengthening the connection therebetween, with corresponding change in the length of the outlet structure. With proper application of the teachings of our invention an automatically drained trap or the like can be constructed with any reasonably sized liquid reservoir, without significant modification of the automatic valving means employed therein.

The aforementioned oil skimmer can be associated with the aforementioned automatic valving device so that the skimmer cooperates with the outlet structure of the trap and one of the automatic valving device float for controlling the discharge of liquid from the trap. When thus arranged the oil skimmer performs its skimming action shortly before the aforementioned float structure terminates the discharge of liquid to prevent the accumulation of oil or other lighter liquid upon a heavier liquid such as water contained within the trap.

We desirably provide in an automatic valving device, the combination comprising a receiver for liquid, an elongated float structure disposed generally vertically in said receiver and including an upper float portion positioned in an upper region of said receiver and a lower float portion positioned in a lower region of said receiver, inlet and outlet port means for said receiver, discharge valve means for said receiver coupled to said outlet port means, said float structure being coupled to said discharge valve means for opening and closing said discharge valve means in response to changes in liquid level in said receiver, biasing means coupled to said discharge valve means for urging said discharge valve means to its closed position, the buoyancy of said float structure lower portion although submerged being insufficient to overcome said biasing means and to open said pilot valve when closed, the buoyancy of said float structure lower portion when fully submerged together with the buoyancy of said float structure upper portion when at least partially submerged being sufficient to overcome said biasing means and to open said discharge valve means at an upper limit level of liquid in said receiver and the total weight of said float structure and of the coupling thereof to said discharge valve means in conjunction with said biasing means being capable of closing said discharge valve means at a lower limit level of liquid in said receiver against the buoyancy of said float structure lower portion when at least partially submerged.

We also desirably provide a similar structure wherein skimming means are disposed adjacent said outlet port means for skimming an overlying layer of a lighter liquid upon juxtaposition of the level of liquid within said receiver to said skimming means during discharge through said discharge valve means.

We also desirably provide in an automatic valving device, the combination comprising a receiver for liquid, a float structure including a main float positioned generally in an upper region of said receiver and an auxiliary float positioned in a lower region of said receiverand an auxiliary float positioned in a lower region of said receiver, said auxiliary float being connected to said main float for movement therewith, inlet and outlet port means in said receiver, discharge valve means coupled to said outlet port means, said float structure being coupled to said discharge valve means for opening and closing said discharge valve means in response to changes in liquid level in said receiver, biasing means coupled to said discharge valve means for urging said discharge valve means to its closed position, the buoyancy of said auxiliary float alone although fully submerged being insufficient to overcome said biasing means and to open said discharge valve means when closed, the combined buoyancy of said auxiliary float when fully submerged and the buoyancy of said main float when at least partially submerged being sufficient to overcome said biasing means and to open said pilot valve at an upper limit level of liquid in said receiver, and the total weight of said float structure and its coupling to said discharge valve means in conjunction with said biasing means being capable of closing said discharge valve means ata lower limit level of liquid in said receiver against the buoyancy of said auxiliary float when at least partially submerged.

We also desirably provide in an automatic valving device, the combination comprising a receiver for liquid, a float structure including a main float positioned generally in an upper region of said receiver and an auxiliary float positioned generally in a lower region of said receiver, said auxiliary float being connected to said main float for movement therewith, an outlet structure for said receiver disposed adjacent the bottom thereof and including a discharge valve, a pilot valve, pressure sensitive means coupling said pilot valve and said discharge valve for opening and closing said discharge valve, an inlet port in said receiver for admittance of a pressurized medium, said float structure being connected to said pilot valve for opening and closing said pilot valve in response to changes in liquid level within said receiver, biasing means connected to said pilot valve and to said float structure for urging said pilot valve to its closed position, the buoyancy of said auxiliary float alone although fully submerged being insufficient to overcome said biasing means and to open said pilot valve when closed, the combined buoyancy of said auxiliary float when fully submerged and of said main float when at least partially submerged being sufficient to overcome said biasing means and to open said pilot valve at an upper limit level of liquid in said receiver, and the combined weights of said float structure and of the connection thereof to said pilot valve in conjunction with said biasing means being capable of closing said pilot valve at a lower limit level of liquid in said receiver against the buoyancy of said auxiliary float when at least partially submerged.

We also desirably provide in a valving device, the combination comprising a receiver for liquid, an outlet structure positioned in the bottom portion of said receiver and including a discharge valve, means for opening and closing said discharge valve, said outlet structure comprising a skimmer tube communicating with said outlet structure and mounted adjacent said discharge valve for skimming a layer of lighter liquid overlying a volume of heavier liquid contained within said reservoir, said skimmer tube including a top opening positioned above said discharge valve and lateral flow aperture means juxtaposed to said discharge valve.

During the foregoing discussion, various objects, features and advantages of the invention have been set forth. These and other objects, features and advantages of the invention together with structural details thereof will be elaborated upon during the forthcoming description of certain presently preferred embodiments of the invention and presently preferred methods of practicing the same.

In the accompanying drawings we have shown certain presently preferred embodiments of the invention and have illustrated certain presently preferred methods of practicing the same, wherein:

FIG. 1 is a vertically sectioned view of one form of automatic valving device, arranged here in the form of an automatic drain trap and illustrating the principles of our invention;

FIG. 1A is a similar view of the apparatus as shown in FIG. 1, but showing the automatic valving device in its opened position;

FIG. 1B is a partial cross-sectional view of the apparatus as shown in FIG. 1 and taken along reference line IBIB thereof;

FIG. 2 is a similar view of another form of our automatic valving device, shown here with means for enhancing the volumetric capacity of the device; and

FIG. 3 is a similar view which illustrates a further increase in volumetric capacity, in accordance with the invention, without significant modification of the automatic valving means.

With more particular reference now to FIGS. 1, 1A and IB of the drawings, our novel automatic drain device 10 illustrated therein is arranged in the form of an automatically drained trap for water and oil or other contaminating liquids. The device 10 comprises a housing 12 which incorporates inlet port means 14 whereby the housing 12 can be connected to a compressed air system or other arrangement maintained under pressure. The housing 12 further includes in this arrangement an upper section 16 and a lower section 18, each of which is flanged at 20 for interconnection by a number of mounting bolts 22. A baffle and seal ring retainer 24 is supported within the housing 12 and includes a skirt section 26 having a circumferential projection 28 for engagement with an O-ring 30 or other sealing device to support the sealing device at the junction between the housing sections 16, 18 as shown. An upper or baffle section 32 of the retainer 24 underlies the inlet port 14 for the purpose of catching and retaining any particulate foreign matter that may enter the port 14 from the system to be drained by the device 10. The baffle and sealing member 32 is further provided with a plate extension 31 which is notched at 33 for partially but closely surrounding the orifice tube 50 for stabilizing purposes.

Supported within the housing 12 is an automatic valving device 34 which is similar in certain respects to that shown in our aforementioned patent, and for which such similarities will not be described in abundant detail. The automatic valving device 34 of our present invention includes a float structure having an upper or main float 36 more or less rigidly mounted on valving arm 38 which is pivoted at 46 and counterweighted at 42. The float 36 and the coupling or arm 38 operate discharge valve means including in this example a pilot valve having'a valve member 641 also mounted on the arm 38 and pressure orifice 46, when the arm 38 is in its more or less horizontal position, as shown. In such position, suitable biasing means, such as a pennanent magnet 48 mounted on orifice tube 56, retain the arm 38in its orificeclosing position "as shown in HO. 1, until a substantial proportion of the main float 36 is submerged by a rising liquid level 52 within the reservoir or receiver 76. At such time, the buoyancy of the float 36 in cooperation with the weight of the counterweight 42 overcomes the magnetic attraction of the magnet 48 and the arm 38 is displaced, counterclockwise in this example, to an open position (FIG. 1A) of the valving device 34.

At such time, a small portion of the compressed air or other fluid from the system (not shown) coupled to the trap inlet port 14 can pass through the valve orifice d6 whence it proceeds downwardly through orifice tube ll to enter cylinder 54 or other suitable pressure-sensitive actuating means. Piston 56 is urged upwardly within the cylinder 54 car rying with it the orifice tube 56 and discharge valve member 58, which is thereby displaced from its valve seat 66. The contained liquid 52, then is free to enter outlet port means or discharge port structure 62 including its supporting tube 64 which is spaced radially outwardly from the orifice tube 50 passing therethrough. The liquid 52 which enters the valve seat 66, flows downwardly (arrows 63, FIG. IA) between the outlet structure support tube 64 and the orifice tube 56 and exits through outlet port 66 (arrow 67).

Discharge of the liquid from the reservoir 76 continues until the liquid level falls approximately to a minimum level position denoted by chain line 68 at which time the arm 38 becomes reengaged with the permanent magnet 48 to close the pressure orifice 46. It will be appreciated that the reactive moment of the mass comprising the float 36 exceeds that comprising the counterweight 42 such that the float 36 follows the liquid level downwardly as the trap 16 discharges until the arm 38 reengages the magnet 48 to terminate both further discharge of liquid from the trap 16 and further movement of the arm 38 in the clockwise direction. At this position of the automatic valving device 34, its liquid reservoir 76 commenced to refill depending upon the extent of liquid contamination within the system to which the inlet port M is coupied.

The arm structure 38 including the float 36 and counterweight 62 move upwardly and downwardly with the orifice tube 56 under impetus of the aforementioned piston 56 as controlled by pilot valve 46-86. When the pressure orifice 46 at the top of the orifice tube 56 is reclosed, the weight of these components forces the piston 56 downwardly until the discharge valve member 58 reengages the valve seat 66. A bleed aperture 72 is provided in the cylinder 54 to relieve the pressure (arrows 73-FIG. llA) after each closure of the valved orifice 46 to permit downward movement of the piston 56. The orifice tube 56 and associate components are stabilized within the support tube 6 1 of the outlet structure 62 by a close engagement of thickened portion 74 at the lower end of the orifice tube 56 within the bore 76 of the support tube 62.

A manual drain cock 77 can be provided for the complete draining of liquid and sediment from the trap reservoir 76 and for other maintenance purposes.

In the automatic valving device as described thus far, the device closes automatically to terminate further liquid discharge when the liquid level 68 adjacent the valve seat 66 is approached. The precise locations of the upper and lower liquid limit levels 52, 68 can be adjusted by adding or replacing washers 69 and/or 711 at the connection of the float 36 with the valving device arm 38. To prevent the possibility of loss of compressed air or other fluid entering the housing inlet port 116 through the outlet tube 66, the automatic valve 34 can be arranged to close before the liquid falls to the minimum level denoted by chain line 68. In any event, these conditions prevent the discharge of any portion of a lighter liquid, such as oil, which can overly a primary entrapped liquid, such as water, as the discharge is terminated before the overlying liquid reaches the valve seat 66, until the overlying liquid has accumulated to a significant depth. In consequence, the volumetric capacity of the reservoir 76 is correspondingly reduced for the primary liquid entrapped, particularly where the overlying liquid offers a significantly reduced buoyancy for the float 36.

To prevent this accumulation of any overlying oil layer, we provide skimming means for such layer which are arranged to become operative shortly before the liquid level within the trap reservoir 76 falls to the control plane, for example the minimum level 68, at which the discharge valve 34 closes. The skimming action of the skimmer relative to the falling liquid surface or interface becomes operative each time the valving device 34 discharges so that there is no opportunity for oil or other light liquid to build up on the primary liquid surface, although the light liquid may collect in the trap only during particular fill and drain cycles.

One form of such skimming means, in accordance with our invention, includes a skimmer tube 78, which is furnished with a top opening 86 and a number of lateral apertures 82 displaced downwardly of the top opening. The skimmer tube 78 is otherwise for the most part spaced in outward, radial relation to the support tube 68 forming part of the outlet structure 62, and is secured to the support tube 64, for example by a throat section 84 closely engaged with the support tube 64 and positioned thereon by circumferential shoulder 86. The skimmer tube 78, therefore, also surrounds the discharge valve member 58 and valve seat 66 described above.

Until the liquid level within the reservoir 76 of the trap 10 recedes to the top opening 86 of the skimmer tube 78, the liquid being discharged enters the valve seat 66 from both the apertures 82 and the top opening 86 of the skimmer tube 78 as denoted by the aforementioned flow arrows 63 and by flow arrows 88 (FIG. IA) respectively. The primary discharge flow, however, is through the apertures 82 which are juxtaposed to the valve member 58 and valve seat 66 in their open position (FIG. IA), or, in other terms, the skimmer tube apertures 82 are disposed in outward radial relation to opening 96 between the valve member 58 and the valve seat 66 and approximately at the same elevation. Thus a direct flow path for the discharg' ing liquid exists through the skimmer apertures 82 to the valve opening 96.

The number and size of the skimmer tube apertures 82 is variable in dependence upon a specific application of the invention. Thus, the size and number of the skimmer tube apertures 82 will depend upon the capacity of the liquid trap 16, the viscosity of the liquid or liquids entrapped therein, the valve opening 96 and size of the outlet flow path defined by the bore 76 of the outlet tube 64, and the size of the outlet port 66. In general the combined areas of the skimmer tube apertures 82 should be less than that of the skimmer tube top opening 86. In the illustrated example of the invention, four such apertures 82 are employed, as evident from FIG. 18 of the drawings.

The operation of the automatic valving means 341 of the trap 116 as shown in FIG. 11 is substantially similar to that of our aforementioned patent, with the exception that the liquid flows primarily through skimmer tube apertures 82 and secondarily through its top opening 86 to the valve opening 96 as shown in H6. ilA. This situation attains until the falling liquid level reaches a plane defined by chain line 92 (FIG. llA) adjacent the top opening 86 of the skimmer tube 78. At such time, the skimming action of the skimmer tube 78 commences. Although the precise flow mechanism whereby the skimming action takes place is not fully understood, it is evident, that, with the liquid level in the area of the plane 92 in FIG. 1A, the entire surface or interface of the descending liquid level is rapidly drawn off into the top skimmer tube opening 80. This skimming of the entire liquid level surface of interface carries with it any overlying oil or other lighter liquid contained on the primary liquid 94 within the trap reservoir 70.

One possible explanation of this phenomenon involves the formation of a vortex about the top opening 80 of the skimmer tube 78 which rapidly draws all of the surface liquid from the farthest reaches of the liquid surface or interface within the trap reservoir 70. Such more or less radial sweeping action across the liquid surface apparently is formed by the cooperative action of pressure upon the liquid surface or interface 92 as it nears the top opening 80 of the skimmer tube 78 (arrows 96-FIG. 1A) and the suctional effects of the discharging liquid flowing through the skimmer tube apertures 82 and the valving device opening 90 (arrows 63). This sweeping action is centered of course, at the skimmer tube opening 80. During the skimming operation, a combination of compressed fluid, any overlying lighter liquid, and primary entrapped liquid is discharged through the outlet structure 62. Such skimming action continues only when the discharging liquid level, such as the level 92, is near the top opening 80 of the skimmer tube 78. In testing our novel apparatus we have purposely added 20 percent oil with 80 percent water to fill the reservoir 70 (or the reservoir 104 or 106 of FIGS. 2 or 3). In this test the overlying oil was expelled virtually in its entirety, from the trap in only three operating cycles.

When the liquid level falls below the top of the skimmer tube 78, and proceeds toward the lower limit level 68 (FIG. 1), the skimming action ceases although liquid continues to discharge through the valving device' opening 90 and skimmer apertures 82 until the valving device 34 closes, as described previously.

After the liquid level has descended below the top opening 80 of the skimmer tube 78, and until the liquid level falls to the closing or lower limit level 68 (FIG. 1) very little of the compressed fluid is discharged through the skimmer tube 78, as the fluid flow is then almost entirely through the lateral skimmer tube aperture 82. In this connection, the physical size or numbers of the apertures 82 is such as to permit an adequate liquid flow therethrough (arrows 63). Otherwise, an undue flow rate of the air or other compressed medium will continue to be discharged along with the liquid contained in the trap 10. If the skimmer apertures 82 are too small, the liquid contained in the trap is discharged too slowly for effective skimming action, in addition to a potential excessive discharge through the skimmer tube top opening 80 of compressed air or other medium entering the trap housing 12 through its inlet port 14. On the other hand, if the skimmer apertures 82 are too large (along with the discharge valve flow passage 90) the discharging liquid level 92 (FIG. 1A) falls too rapidly and there is almost no skimming action. As a further aid to minimizing the discharge of compressed fluid, the annular area 98 (FIGS. 1 and 1A) between the overhanging peripheral edge 100 of the valve member 58 and the inner bore 102 of the skimmer tube 78 should be approximately equal to or less than the combined areas of the lateral skimmer tube apertures 82.

Depending upon the relative sizes of the trap outlet structure 62 including the skimmer tube opening 80 and apertures 82, the discharge valving opening 90, and the clearance 98 between the valve member 58 and the skimmer tube 78, the aforedescribed skimming action can be maintained between about 12 and about 4 seconds. If the skimming time is shorter than about one-half second an incomplete skimming operation results.

Our invention also contemplates means for increasing the liquid capacity of the trap as illustrated exemplarily by the traps 10a, 10b of FIGS. 2 and 3 respectively. In these figures similar reference characters with prime accents denote similar components of the automatic valving devices 34' (FIG. 2) or 34" (FIG. 3) relative to the valving device 34 of FIGS. 1 and 1A. A significant difference between the valving devices 34',

34" and the valving device 34 of FIG. I lies in the correspondingly longer lengths of the orifice tubes 50a, 50b of the valving devices 34, 34" respectively in order to adapt the valving devices to the correspondingly larger or deeper reservoirs 104, 106 of the traps 10a, 1012 respectively of FIGS. 2 and 3, as described below.

In the same manner, similar reference characters with prime accents denote similar components of the housing structures 12a, 12b of the traps 10a, 10b respectively relative to the housing structure 12 of FIGS. 1 and 1A. Thus in FIG. 2, the housing structure 12a of FIG. 2 includes an upper section 16', which is sealed to a lower, reservoir section 108 with the aid of baffle member 32' and sealing ring 30'. At the lower end of the reservoir housing section 108, the latter is provided with an outlet or exhaust structure 62' and manual drain cock 75 which functions as described previously.

In the automatic valving device 34 of FIG. 2, means are provided for cooperatively delaying opening of the valving device until the level of contained liquid within the reservoir 104 reaches an upper limit level designated by chain line 110, and for delaying closing of the valving device 34 until the level of discharging liquid in the reservoir 104 falls to a lower limit level designated by chain line 112. Such delaying means are afforded primarily through the use of our novel float structure, which includes in this example an auxiliary or lower float 114 spacedly connected to main float 36. The connection is effected by a relatively stiff wire or rod 116 pivotally joined at 118 to an apertured tab 120 secured to the bottom of the upper float 36. The pivot connection is desirable as the upper float 36 and valving arm 38 follow an arcuate path, in the illustrated embodiment.

The other end of the rod 1 16 is more or less rigidly joined to the top of auxiliary float 114. The length of the rod 116 can be varied as required to provide means for readily varying the separation between the upper and lower float portions 36 114 and hence the elevation of the lower liquid level limit 112, for example relative to the top portions of the skimmer tube apertures 82'.

One arrangement for joining the connecting rod 116 to the lower float 114 includes securing the lower end portion of the rod 116 to a threaded bushing 118 which in turn is threadedly engaged with an apertured and tapped insert 120 sealed to the wall structure of the float 114.

The connecting rod 116 and lower or auxiliary float 114 is stabilized in the lateral direction by suitable stabilizing means, such as arm 124 secured to the elongated orifice tube 50a. The stabilizing arm 124 can be fabricated in any convenient fashion, and in this example is formed from spring wire having a turn or two 126 at its outward extremity defining an aperture through which the rod 116 loosely passes. The inward ends of the spring wire 124 are turned about the orifice tube 50a to which they are secured by spot welds 128.

In the operation of the trap 10a, it will be assumed that the contained liquid has just been discharged, and the valve member 58' has receded against the valve seat 60, at which time the level of liquid within the reservoir 104 will be at the lower limit level, 112. As the liquid level increases from the lower limit level 112 the auxiliary float 114 becomes increasingly submerged. The buoyancy of the auxiliary float 114 in this case is less than that of the main float 36' and is insufficient to overcome the discharge valve biasing means, i.e., the magnetic attraction between the magnet 48' and the valving arm 38', even when the auxiliary float 114 is fully submerged. The liquid within the reservoir 104, therefore, continues to rise and to fill the reservoir, until the upper liquid level limit is reached. At this time, the combined buoyancy of the partially submerged main float 36 and of the fully submerged auxiliary float 114 is sufficient to overcome the magnetic attraction between the magnet 48' and the arm 38'. The pressure orifice 46' is opened by lifting of the associated valve member 44' with the result that the exhaust valve member 58' and associated components are lifted to the position similar to that illustrated by the valve member 58 in FIG. 1A. From this time, the liquid contained within the reservoir is discharged until its level again recedes to the lower limit level I I2.

As the liquid level recedes from the main float 36 the weight of the float 36', although entirely removed from the liquid within the reservoir, is inadequate to overcome the counterclockwise moments applied to the valving arm 33 by counterweight 42 and the buoyancy of the still submerged auxiliary float II I. As in the trap III of FIGS. I and IA the counterweight d2 counterbalances only a portion of the weight of the main float 36'. In the traps of FIGS. 2 and 3 however, such counterbalance can be supplied entirely by the buoyancy of the auxiliary float IM or IM', when fully submerged, at intermediate liquid levels. In the latter case, the counterweight 42' can be reduced in size or omitted altogether. In contradistinction to the valving device 3d of the preceding figures, the valving arm 38' remains motionless in its raised or open position similar to that shown by'the valving arm 38 of FIG. IA until shortly before the descending liquid level reaches the lower limit level II2. At this point the auxiliary float I14 begins to emerge from the liquid and the increasing weight of the emerging portions of the auxiliary float H4 in combination with the weight of the main float 36' attains a value (before the liquid surface reaches the lower limit level Ill2) which overcomes the moments introduced in the opposite direction by the counterweight I2 and the residual buoyancy of the emerging auxiliary float II -I. Thereafter the valving arm 3% begins to close, by clockwise displacement in FIG. 2, as the auxiliary float I141 begins to follow the descending liquid level downwardly within the reservoir I04. This continues until the valving arm 38 enters the attractive field of the magnet 48', at which time the pressure orifice an is immediately closed precisely at the lower limit level 1112, to terminate any further discharge of the liquid contained within the reservoir I'M.

The function and construction of the automatic drain trap 10b in FIG. 3 is similar in its essential details. The trap Itlb is endowed with a still larger reservoir I06 by modification of its housing structure I2b. Thus, the housing structure includes a lower section I03 similar to the reservoir section 103 of FIG. 2 but joined to an enlarged upper section I30 to complete the liquid reservoir 1th). Owing to the size of the upper housing section I30, baffle and sealing means corresponding to member 32 or 32' of FIG. I or 2 is separated into an intermediate sealing member I32 and an upper baffle member I34. The lower portion of the baffle member I34 can be provided with a spacing shoulder I36, whereat the baffle member can be spot welded (not shown) or otherwise secured to the upper housing section 139 in the illustrated position. The notched stabilizing plate 31 for the further elongated orifice tube 5017 can be formed integrally with the intermediate sealing member I32 as illustrated, or alternatively with the baffle member I341 (not shown).

To accommodate the automatic valving device 34" to the elongated or deeper reservoir 1% of the trap IIlb, the connecting rod IIda between the main float 36" and the auxiliary float I14 is correspondingly elongated as is the orifice tube 50b in this area. The lower end of the connecting rod 116a and the auxiliary float II I' are stabilized against substantial lateral movement by stabilizing arm 124'. The stabilizing arm 124- as in the case of the arm I24) of FIG. 2 desirably is positioned as low as practical but sufficiently above the threaded bushing 118 or I18 to permit raising of the auxiliary float IM to its chain outlined position I36 when the valving arm 33" and associated components are raised to their open position denoted by chain outline I33.

With the arrangement shown in FIG. 3, the liquid entrapped within the reservoir Illa of trap I012 can be controlled between an upper limit level HQ and a lower liquid I12 in the manner described previously in connection with FIG. 2. It will be apparent from a comparison of FIGS. 2 and 3 that the reservoir I06 can be provided with any practicable height or depth by a corresponding elongated or shortening, as the case may be of III the connecting rod or wire IIIS or 116a (or other relatively rigid member) and of the orifice tube 50a or 50b.

A further note about the structural relationships among the housings I2, 12a, and I2!) of the illustrated modifications (FIGS. I, 2 and 3 respectively) of our invention is in order. For manufacturing simplicity and for a corresponding reduction in parts inventory, the housing sections I6, III of FIG. I and the upper housing section I6 of FIG. 2 can be made of substantially the same size and shape. That is to say for the several illustrated modifications of our invention these sections can be made identical save for providing the lower housing section Id of FIG. I with differing openings for the outlet structure 62 and the manual drain cock 75. In a similar manner, the lower housing section 103 of FIG. 2 and the upper and lower housing sections Illt), 103 of FIG. 3 can be made substantially identical.

With this arrangement, the inside dimensions of the lower housing sections III (FIG. I) 108 (FIG. 2) and I08 (FIG. 3) are identical, and such dimension desirably is optimized with respect to the skimmer tube opening 30 and apertures 82 and to the remaining several passages of the outlet structure 62, 62' and 62 such that the liquid level within the corresponding trap reservoirs does not fall too fast or too slow for an optimized skimming operation. It will be understood that the aforementioned dimensions can be varied from those illustrated in the several figures and with respect to the sizes of the components comprising the outlet structures 62, 62" and 62 as long as an adequate skimming time is afforded, desirably within the range of about one-half second to about 4 seconds. A particular skimming time selected within the aforementioned range will in turn depend upon the anticipated amount of entrapped oil and on the total capacity of the trap reservoir for all liquids to be separated by the trap.

With suitable modification of the outlet structure dimensions, including those of the skimmer tube '73, the valving device 34, 342 or 34" can be installed in differing types of or considerably larger tankage for level or discharge control.

It is noteworthy also to point out that the baffle member 134 of FIG. 3 is substantially identical to the upper portion of the baffle and sealing member 32 (FIG. I.) or 32' (FIG. 2) with the exception that the sealing projection 23 or 28 has been partially milled off to form the spacing shoulder I36 of baffle I34. Similarly the intermediate sealing member I32 corresponds to the lower portion of member 32 or 32.

The modification of our invention as illustrated in either FIG. 2 or FIG. 3 can be provided with skimming means such as the skimmer tube 73 of FIGS. I, IA and IB, for an overlying oil or other lighter liquid layer. In the skimmer tube 73 or 78" of FIGS. 2 or 3, the enlarged portion thereof is elongated such that its top opening III) or 30" is disposed at a higher elevation above the outlet valve seat tit) or as". This provides a more effective skimming action in the larger capacity devices of FIGS. 2 and FIG. 3, where a correspondingly thicker layer of overlying oil or other light liquid is anticipated. The shorter skimming tube 73, of the FIG. I arrangement provides the necessary clearance for the float 36.

From the foregoing it will be apparent that novel and efficient forms of an automatic valving device have been described herein. While we have shown and described certain presently preferred embodiments of the invention and have illustrated presently preferred methods of practicing the same it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the spirit and scope of the invention.

We claim:

I. In an automatic valving device, the combination comprising a receiver for liquid, an elongated float structure disposed generally vertically in said receiver and including an upper float portion positioned in an upper region of said receiver and a lower float portion positioned in a lower region of said receiver, said lower float portion being spacedly secured to said upper float portion, inlet and outlet port means for said receiver, discharge valve means for said receiver coupled to said outlet port means, said float structure being coupled to said discharge valve means for opening and closing said discharge valve means in response to changes in liquid level in said receiver, biasing means coupled to said discharge valve means for urging said discharge valve means to a closed position, the buoyancy of said float structure lower portion although submerged being insufficient to overcome said biasing means and to open said discharge valve means when closed, the buoyancy of said float structure lower portion when fully submerged together with the buoyancy of said float structure upper portion when at least partially submerged being sufficient to overcome said biasing means when said discharge valve means are closed and to open said discharge valve means at an upper limit level of liquid in said receiver, the buoyancy of said lower portion when fully submerged being sufficient to overcome said biasing means and to support at a portion of the weight of said upper float portion when said discharge valve means have been opened and to maintain said discharge valve means in an opened condition at intermediate levels of said liquid, and the total weight of said float structure and of the coupling thereof to said discharge valve means in conjunction with said biasing means being capable of closing said discharge valve means at a lower limit level of liquid in said receiver against any residual buoyancy of said float structure lower portion.

2. In an automatic valving device, the combination comprising a receiver for liquid, a float structure including a main float positioned generally in an upper region of said receiver and an auxiliary float positioned in a lower region of said receiver, said auxiliary float being spacedly connected to said main float for movement therewith, inlet and outlet port means in said receiver, discharge valve means coupled to said outlet port means, said float structure being coupled to said discharge valve means for opening and closing said discharge valve means in response to changes in liquid level in said receiver, biasing means coupled to said discharge valve means for urging said discharge valve means to a closed position, the buoyancy of said auxiliary float alone although fully submerged being insufflcient to overcome said biasing means and to open said discharge valve means when closed, the combined buoyancy of said auxiliary float when fully submerged and the buoyancy of said main float when at least partially submerged being sufficient to overcome said biasing means when said discharge means are closed and to open said discharge valve means at an upper limit level of liquid in said receiver, the buoyancy of said auxiliary float when fully submerged being sufficient to overcome said biasing means and to support at least a portion of the weight of said main float when said discharge valve means have been opened and to maintain said discharge valve means in an opened condition at intermediate levels of said liquid, and the total weight of said float structure and its coupling to said discharge valve means in conjunction with said biasing means being capable of closing said discharge valve means at a lower limit level of liquid in said receiver against any residual buoyancy of said auxiliary float.

3. In an automatic valving device, the combination comprising a receiver for liquid, a float structure including a main float positioned generally in an upper region of said receiver and an auxiliary float positioned generally in a lower region of said receiver, said auxiliary float being spacedly connected to said main float for movement therewith, an outlet structure for said receiver disposed adjacent the bottom thereof and including a discharge valve, a pilot valve, pressure sensitive means coupling said pilot valve and said discharge valve for opening and closing said discharge valve, an inlet port in said receiver for admittance of a pressurized medium, said float structure being connected to said pilot valve for opening and closing said pilot valve in response to changes in liquid level within said receiver, biasing means connected to said pilot valve and to said float structure for urging said pilot valve to a closed position, the buoyancy of said auxiliary float alone although fully submerged being insufficient to overcome said biasing means and to open said pilot valve when closed, the combined buoyancy of said auxiliary float when fully submerged and of said main float when at least partially submerged being sufficient to overcome said biasing means when said pilot valve is closed and to open said pilot valve at an upper limit level of liquid in said receiver, the buoyancy of said auxiliary float when fully submerged being sufficient to overcome said biasing means and to support at least a portion of the weight of said main float when said pilot valve has been opened and to maintain said pilot valve in an opened condition at intermediate levels of said liquid, and the combined weights of said float structure and of the connection thereof to said pilot valve in conjunction with said biasing means being capable of closing said pilot valve at a lower limit level of liquid in said receiver against any residual buoyancy of said auxiliary float.

4. The combination according to claim 1 wherein counterv weight means are attached to said discharge valve meansfloat structure coupling to counterbalance the weight of said float structure to permit closure of said discharge valve means at a correspondingly lesser submergence of said float structure lower portion auxiliary float.

5. The combination according to claim 2 wherein said float structure includes an elongated connecting member joining said main float and said auxiliary float for substantially common movement of said floats longitudinally of said connecting member.

6. In an automatic valving device, the combination comprising a receiver for liquid, a float structure including a main float positioned generally in an upper region of said receiver and an auxiliary float positioned generally in a lower region of said receiver, said auxiliary float being connected to said main float for movement therewith, an outlet structure for said receiver disposed adjacent the bottom thereof and including a discharge valve, a pilot valve, pressure sensitive means coupling said pilot valve and said discharge valve for opening and closing said discharge valve, an inlet port in said receiver for admittance of a pressurized medium, said float structure being connected to said pilot valve for opening and closing said pilot valve in response to changes in liquid level within said receiver, biasing means connected to said pilot valve and to said float structure for urging said pilot valve to its closed position, the buoyancy of auxiliary float alone although fully submerged being insufficient to overcome said biasing means and to open said pilot valve when closed, the combined buoyancy of said auxiliary float when fully submerged and of said main float when at least partially submerged being suffrcient to overcome said biasing means and to open said pilot valve at an upper limit level of liquid in said receiver, the combined weights of said float structure and of the connection thereof to said pilot valve in conjunction with said biasing means being capable of closing said pilot valve at a lower limit level of liquid in said receiver against the buoyancy of said auxiliary float when at least partially submerged, said pressure sensitive means including an orifice tube extending from said pilot valve to actuating means coupled to said discharge valve and likewise forming part of said pressure sensitive means, said floats being joined by an elongated connecting member, said orifice tube and said elongated connecting member extending substantially parallel, and stabilizing means secured to said orifice tube for loosely engaging said connecting member to permit relative longitudinal movement therebetween but to restrain lateral movement of said connecting member and said auxiliary float relative to said orifice tube.

7. In an automatic valving device, the combination comprising a receiver for liquid, a float structure including a main float positioned generally in an upper region of said receiver and an auxiliary float positioned in a lower region of said receiver, said auxiliary float being connected to said main float for movement therewith, inlet and outlet port means in said receiver, discharge valve means coupled to said outlet port means, said float structure being coupled to said discharge valve means for opening and closing said discharge valve means in response to changes in liquid level in said receiver, biasing means coupled to said discharge valve means for urging sa d discharge valve means to its closed position, the buoyancy of said auxiliary float alone although fully submerged being insufficient to overcome said biasing means and to open said discharge valve means when closed, the combined buoyancy of said auxiliary float when fully submerged and the buoyancy of said main float when at least partially submerged being sufficient to overcome said biasing means and to open said pilot valve at an upper limit level of liquid in said receiver, the total weight of said float structure and its coupling to said discharge valve means in conjunction with said biasing means being capable of closing said discharge valve means at a lower limit level of liquid in said receiver against the buoyancy of said auxiliary float when at least partially submerged, said float structure including an elongated connecting member joining said main float and said auxiliary float for substantially common movement of said floats longitudinally of said connecting member, said connecting member including means for adjusting the length thereof in order to correspondingly adjust the distance between said main float and said auxiliary float and the distance between said upper and lower liquid levels.

d. ln an automatic valving device, the combination comprising a receiver for liquid, an elongated float structure disposed generally vertically in said receiver and including an upper float portion positioned in an upper region of said receiver and a lower float portion positioned in a lower region of said receiver, inlet and outlet port means for said receiver, discharge valve means for said receiver coupled to said outlet port means, said float structure being coupled to said discharge valve means for opening and closing said discharge valve means in response to changes in liquid level in said receiver, biasing means coupled to said discharge valve means for urging said discharge valve means to its closed position, the buoyancy of said float structure lower portion although submerged being insufficient to overcome said biasing means and to open said discharge valve means when closed, the buoyancy of said float structure lower portion when fully submerged together with the buoyancy of said float structure upper portion when at least partially submerged being sufficient to overcome said biasing means and to open said discharge valve means at an upper limit level of liquid in said receiver, the total weight of said float structure and of the coupling thereof to said discharge valve means in conjunction with said biasing means being capable of closing said discharge valve means at a lower limit level of liquid in said receiver against the buoyancy of said float structure lower portion when at least partially submerged, skimming means disposed adjacent said outlet port means for skimming an overlying layer of lighter liquid, said float structure and said discharge valve means being so related that upon lowering of said float structure and imminent closure of said valve means thereby said liquid level is slightly above the top of said skimming means.

9. The combination according to claim d wherein said skimming means are mounted on said outlet port means and spacedly surround said discharge valve means.

it). The combination according to claim 9 wherein said discharge valve means includes a valve member and a valve seat positioned within said receiver and adjacent the bottom thereof, and said skimming means include a tubular member having an open top projecting above said valve seat and lateral flow apertures juxtaposed to said valve seat so as to be disposed substantially at the same elevation of said valve seat, said tubular member spacedly surrounding said valve member.

1111. The combination according to claim 9 wherein said skimming means include a tubular member having an open id top projecting above said discharge valve means and lateral flow apertures juxtaposed to said discharge valve means, said lateral tubular member apertures being less in total flow area than that of said tubular member top opening.

The combination according to claim ill wherein the spacing between said tubular member and said discharge valve means is about equal to the total area of said tubular member lateral apertures.

113. The combination according to claim 10 wherein a discharge valve opening between said valve member and said valve seat at the open position of said discharge valve is about equal to the spacing between said valve member and said tubular member.

114. The combination according to claim 13 wherein said tubular member opening and apertures, said spacing, and said discharge valve opening are proportioned within a range of respective shapes such that a deviation of said proportioning from said range in one direction produces a too rapid drop in liquid level during discharging for effective skimming action and a deviation of said proportioning in the opposite direction from said range produces too slow a drop in said liquid level for effective skimming action.

15. The combination according to claim ll4l wherein the inner horizontal dimensions of said receiver are interrelated with said proportioned shapes to effect a predetermined rate of fall in liquid level to effect an optimum duration of skimming action.

lib. In a valving device, the combination comprising a receiver for liquid, an outlet structure positioned in the bottom portion of said receiver and including a discharge valve, means including a float structure for opening and closing said discharge valve, said outlet structure comprising a skimmer tube communicating with said outlet structure and mounted adjacent said discharge valve for skimming a layer of lighter liquid overlying a volume of heavier liquid contained within said reservoir, said skimmer tube including a top opening positioned above said discharge valve and lateral flow aperture means juxtaposed to said discharge valve, and said float structure and said discharge valve closing means being so related that upon lowering of said float structure and imminent closure of said discharge valve thereby said liquid level is slightly above said skimmer tube top opening.

117. The combination according to claim l6 wherein the area of said lateral aperture means is less than that of said skimmer tube opening.

llli. The combination according to claim 17 wherein the spacing between said skimmer tube and said discharge valve is about equal to the total area of said lateral aperture means.

119. The combination according to claim i8 wherein said skimmer tube spacedly surrounds said discharge valve, and a discharge flow passage through said valve at the open position thereof is about equal to the spacing between said discharge valve and said skimmer tube.

20. The combination according to claim 19 wherein said skimmer tube top opening and lateral aperture means, said spacing, said discharge valve passage are proportioned within a range of shapes such that a deviation of said proportioning from said range in one direction produces a too rapid drop in liquid level during discharging for effective skimming action and a deviation of said proportioning in the opposite direction from said range produces too slow a drop in liquid level for effective skimming action.

M. The combination according to claim 20 wherein the inner horizontal dimensions of said receiver are interrelated with said proportioned shapes to effect a predetermined rate of fall in liquid level to effect an optimum duration of said skimming action. 

1. In an automatic valving device, the combination comprising a receiver for liquid, an elongated float structure disposed generally vertically in said receiver and including an upper float portion positioned in an upper region of said receiver and a lower float portion positioned in a lower region of said receiver, said lower float portion being spacedly secured to said upper float portion, inlet and outlet port means for said receiver, discharge valve means for said receiver coupled to said outlet port means, said float structure being coupled to said discharge valve means for opening and closing said discharge valve means in response to changes in liquid level in said receiver, biasing means coupled to said discharge valve means for urging said discharge valve means to a closed position, the buoyancy of said float structure lower portion although submerged being insufficient to overcome said biasing means and to open said discharge valve means when closed, the buoyancy of said float structure lower portion when fully submerged together with the buoyancy of said float structure upper portion when at least partially submerged being sufficient to overcome said biasing means when said discharge valve means are closed and to open said discharge valve means at an upper limit level of liquid in said receiver, the buoyancy of said lower portion when fully submerged being sufficient to overcome said biasing means and to support at a portion of the weight of said upper float portion when said discharge valve means have been opened and to maintain said discharge valve means in an opened condition at intermediate levels of said liquid, and the total weight of said float structure and of the coupling thereof to said discharge valve means in conjunction with said biasing means being capable of closing said discharge valve means at a lower limit level of liquid in said receiver against any residual buoyancy of said float structure lower portion.
 2. In an automatic valving device, the combination comprising a receiver for liquid, a float structure including a main float positioned generally in an upper region of said receiver and an auxiliary float positioned in a lower region of said receiver, said auxiliary float being spacedly connected to said main float for movement therewith, inlet and outlet port means in said receiver, discharge valve means coupled to said outlet port means, said float structure being coupled to said discharge valve means for opening and closing said discharge valve means in response to changes in liquid level in said receiver, biasing means coupled to said discharge valve means for urging said discharge valve means to a closed position, the buoyancy of said auxiliary float alone although fully submerged being insufficient to overcome said biasing means and to open said discharge valve means when closed, the combined buoyancy of said auxiliary float when fulLy submerged and the buoyancy of said main float when at least partially submerged being sufficient to overcome said biasing means when said discharge means are closed and to open said discharge valve means at an upper limit level of liquid in said receiver, the buoyancy of said auxiliary float when fully submerged being sufficient to overcome said biasing means and to support at least a portion of the weight of said main float when said discharge valve means have been opened and to maintain said discharge valve means in an opened condition at intermediate levels of said liquid, and the total weight of said float structure and its coupling to said discharge valve means in conjunction with said biasing means being capable of closing said discharge valve means at a lower limit level of liquid in said receiver against any residual buoyancy of said auxiliary float.
 3. In an automatic valving device, the combination comprising a receiver for liquid, a float structure including a main float positioned generally in an upper region of said receiver and an auxiliary float positioned generally in a lower region of said receiver, said auxiliary float being spacedly connected to said main float for movement therewith, an outlet structure for said receiver disposed adjacent the bottom thereof and including a discharge valve, a pilot valve, pressure sensitive means coupling said pilot valve and said discharge valve for opening and closing said discharge valve, an inlet port in said receiver for admittance of a pressurized medium, said float structure being connected to said pilot valve for opening and closing said pilot valve in response to changes in liquid level within said receiver, biasing means connected to said pilot valve and to said float structure for urging said pilot valve to a closed position, the buoyancy of said auxiliary float alone although fully submerged being insufficient to overcome said biasing means and to open said pilot valve when closed, the combined buoyancy of said auxiliary float when fully submerged and of said main float when at least partially submerged being sufficient to overcome said biasing means when said pilot valve is closed and to open said pilot valve at an upper limit level of liquid in said receiver, the buoyancy of said auxiliary float when fully submerged being sufficient to overcome said biasing means and to support at least a portion of the weight of said main float when said pilot valve has been opened and to maintain said pilot valve in an opened condition at intermediate levels of said liquid, and the combined weights of said float structure and of the connection thereof to said pilot valve in conjunction with said biasing means being capable of closing said pilot valve at a lower limit level of liquid in said receiver against any residual buoyancy of said auxiliary float.
 4. The combination according to claim 1 wherein counterweight means are attached to said discharge valve means-float structure coupling to counterbalance the weight of said float structure to permit closure of said discharge valve means at a correspondingly lesser submergence of said float structure lower portion auxiliary float.
 5. The combination according to claim 2 wherein said float structure includes an elongated connecting member joining said main float and said auxiliary float for substantially common movement of said floats longitudinally of said connecting member.
 6. In an automatic valving device, the combination comprising a receiver for liquid, a float structure including a main float positioned generally in an upper region of said receiver and an auxiliary float positioned generally in a lower region of said receiver, said auxiliary float being connected to said main float for movement therewith, an outlet structure for said receiver disposed adjacent the bottom thereof and including a discharge valve, a pilot valve, pressure sensitive means coupling said pilot valve and said discharge valve for opening and closing said discharge valve, an inlet port in said receiver for admittance of a pressurized medium, said float structure being connected to said pilot valve for opening and closing said pilot valve in response to changes in liquid level within said receiver, biasing means connected to said pilot valve and to said float structure for urging said pilot valve to its closed position, the buoyancy of auxiliary float alone although fully submerged being insufficient to overcome said biasing means and to open said pilot valve when closed, the combined buoyancy of said auxiliary float when fully submerged and of said main float when at least partially submerged being sufficient to overcome said biasing means and to open said pilot valve at an upper limit level of liquid in said receiver, the combined weights of said float structure and of the connection thereof to said pilot valve in conjunction with said biasing means being capable of closing said pilot valve at a lower limit level of liquid in said receiver against the buoyancy of said auxiliary float when at least partially submerged, said pressure sensitive means including an orifice tube extending from said pilot valve to actuating means coupled to said discharge valve and likewise forming part of said pressure sensitive means, said floats being joined by an elongated connecting member, said orifice tube and said elongated connecting member extending substantially parallel, and stabilizing means secured to said orifice tube for loosely engaging said connecting member to permit relative longitudinal movement therebetween but to restrain lateral movement of said connecting member and said auxiliary float relative to said orifice tube.
 7. In an automatic valving device, the combination comprising a receiver for liquid, a float structure including a main float positioned generally in an upper region of said receiver and an auxiliary float positioned in a lower region of said receiver, said auxiliary float being connected to said main float for movement therewith, inlet and outlet port means in said receiver, discharge valve means coupled to said outlet port means, said float structure being coupled to said discharge valve means for opening and closing said discharge valve means in response to changes in liquid level in said receiver, biasing means coupled to said discharge valve means for urging said discharge valve means to its closed position, the buoyancy of said auxiliary float alone although fully submerged being insufficient to overcome said biasing means and to open said discharge valve means when closed, the combined buoyancy of said auxiliary float when fully submerged and the buoyancy of said main float when at least partially submerged being sufficient to overcome said biasing means and to open said pilot valve at an upper limit level of liquid in said receiver, the total weight of said float structure and its coupling to said discharge valve means in conjunction with said biasing means being capable of closing said discharge valve means at a lower limit level of liquid in said receiver against the buoyancy of said auxiliary float when at least partially submerged, said float structure including an elongated connecting member joining said main float and said auxiliary float for substantially common movement of said floats longitudinally of said connecting member, said connecting member including means for adjusting the length thereof in order to correspondingly adjust the distance between said main float and said auxiliary float and the distance between said upper and lower liquid levels.
 8. In an automatic valving device, the combination comprising a receiver for liquid, an elongated float structure disposed generally vertically in said receiver and including an upper float portion positioned in an upper region of said receiver and a lower float portion positioned in a lower region of said receiver, inlet and outlet port means for said receiver, discharge valve means for said receiver coupled to said outlet port means, said float structure being cOupled to said discharge valve means for opening and closing said discharge valve means in response to changes in liquid level in said receiver, biasing means coupled to said discharge valve means for urging said discharge valve means to its closed position, the buoyancy of said float structure lower portion although submerged being insufficient to overcome said biasing means and to open said discharge valve means when closed, the buoyancy of said float structure lower portion when fully submerged together with the buoyancy of said float structure upper portion when at least partially submerged being sufficient to overcome said biasing means and to open said discharge valve means at an upper limit level of liquid in said receiver, the total weight of said float structure and of the coupling thereof to said discharge valve means in conjunction with said biasing means being capable of closing said discharge valve means at a lower limit level of liquid in said receiver against the buoyancy of said float structure lower portion when at least partially submerged, skimming means disposed adjacent said outlet port means for skimming an overlying layer of lighter liquid, said float structure and said discharge valve means being so related that upon lowering of said float structure and imminent closure of said valve means thereby said liquid level is slightly above the top of said skimming means.
 9. The combination according to claim 8 wherein said skimming means are mounted on said outlet port means and spacedly surround said discharge valve means.
 10. The combination according to claim 9 wherein said discharge valve means includes a valve member and a valve seat positioned within said receiver and adjacent the bottom thereof, and said skimming means include a tubular member having an open top projecting above said valve seat and lateral flow apertures juxtaposed to said valve seat so as to be disposed substantially at the same elevation of said valve seat, said tubular member spacedly surrounding said valve member.
 11. The combination according to claim 9 wherein said skimming means include a tubular member having an open top projecting above said discharge valve means and lateral flow apertures juxtaposed to said discharge valve means, said lateral tubular member apertures being less in total flow area than that of said tubular member top opening.
 12. The combination according to claim 11 wherein the spacing between said tubular member and said discharge valve means is about equal to the total area of said tubular member lateral apertures.
 13. The combination according to claim 10 wherein a discharge valve opening between said valve member and said valve seat at the open position of said discharge valve is about equal to the spacing between said valve member and said tubular member.
 14. The combination according to claim 13 wherein said tubular member opening and apertures, said spacing, and said discharge valve opening are proportioned within a range of respective shapes such that a deviation of said proportioning from said range in one direction produces a too rapid drop in liquid level during discharging for effective skimming action and a deviation of said proportioning in the opposite direction from said range produces too slow a drop in said liquid level for effective skimming action.
 15. The combination according to claim 14 wherein the inner horizontal dimensions of said receiver are interrelated with said proportioned shapes to effect a predetermined rate of fall in liquid level to effect an optimum duration of skimming action.
 16. In a valving device, the combination comprising a receiver for liquid, an outlet structure positioned in the bottom portion of said receiver and including a discharge valve, means including a float structure for opening and closing said discharge valve, said outlet structure comprising a skimmer tube communicating with said outlet structure and mounted adjacent said discharge valve for skimming a layer of lighter liquid Overlying a volume of heavier liquid contained within said reservoir, said skimmer tube including a top opening positioned above said discharge valve and lateral flow aperture means juxtaposed to said discharge valve, and said float structure and said discharge valve closing means being so related that upon lowering of said float structure and imminent closure of said discharge valve thereby said liquid level is slightly above said skimmer tube top opening.
 17. The combination according to claim 16 wherein the area of said lateral aperture means is less than that of said skimmer tube opening.
 18. The combination according to claim 17 wherein the spacing between said skimmer tube and said discharge valve is about equal to the total area of said lateral aperture means.
 19. The combination according to claim 18 wherein said skimmer tube spacedly surrounds said discharge valve, and a discharge flow passage through said valve at the open position thereof is about equal to the spacing between said discharge valve and said skimmer tube.
 20. The combination according to claim 19 wherein said skimmer tube top opening and lateral aperture means, said spacing, said discharge valve passage are proportioned within a range of shapes such that a deviation of said proportioning from said range in one direction produces a too rapid drop in liquid level during discharging for effective skimming action and a deviation of said proportioning in the opposite direction from said range produces too slow a drop in liquid level for effective skimming action.
 21. The combination according to claim 20 wherein the inner horizontal dimensions of said receiver are interrelated with said proportioned shapes to effect a predetermined rate of fall in liquid level to effect an optimum duration of said skimming action. 